bug: Android Web Login Flow Crashes or Fails When Using Flutter SDK with Custom Tabs

[PraiseJahFrancis]

Describe the bug

When integrating the logto_dart_sdk in a Flutter app, the sign-in flow on Android crashes or fails to complete when the signIn() method is called. This only occurs on Android and works perfectly on iOS.

The SDK attempts to launch a browser using Android Custom Tabs, but fails with: W/CustomTabsClient: Unable to find any Custom Tabs packages, you may need to add a element to your manifest.
PlatformException(CANCELED, User canceled login, null, null)
The signIn() method never completes and throws a PlatformException with the message User canceled login. Even when the redirect URL is received successfully

I put this is my manifest file





I still get errors like
W/CustomTabsClient: Unable to find any Custom Tabs packages...
PlatformException(CANCELED, User canceled login, null, null)
LogtoAuthException(LogtoAuthExceptions.isLoadingError): Already signing in...

Expected behavior

Browser opens using Custom Tabs
User logs in
App receives redirect URI
SDK successfully handles token exchange and signs in

How to reproduce?

Add logto_dart_sdk to a Flutter project.

Configure a valid redirectUri (e.g., com.example.app://callback) in the Logto dashboard and AndroidManifest.xml.
Call logtoClient.signIn() on Android.
Observe
Either the browser fails to open,
Or it opens and returns, but the SDK throws PlatformException(CANCELED, User canceled login) and logs LogtoAuthExceptions.isLoadingError: Already signing in.

Environment

Logto Cloud

Screenshots

No response

[cheezone]

@gao-sun @charIeszhao

Issue: Registration flow interrupted when user switches to email app to check verification code

Problem Description

I'm experiencing a critical UX issue with the authentication flow when users need to register (not login) using email verification. Here's the scenario:

1. User clicks "Sign In" → Opens Logto authentication page
2. User starts registration → Enters email address
3. System sends verification code → User needs to check email
4. User switches to email app → To view the verification code
5. User returns to app → The registration page disappears!
6. User tries again → Gets a new verification code, creating an infinite loop

Root Cause

The issue occurs because:

• When users switch to their email app to check verification codes, the app goes to background
• The authentication flow gets interrupted and the web view/page is destroyed
• When users return, they're back to the main app screen instead of the registration page
• This creates a dead loop where users can never complete registration

Expected Behavior

Users should be able to:

1. Start registration in the app
2. Switch to email app to check verification code
3. Return to the app and continue the registration process
4. Complete registration without the page disappearing

Technical Details

• Platform: Android (Flutter)
• SDK Version: logto_dart_sdk: ^3.0.0
• Authentication Method: Email verification
• Issue: flutter_web_auth_2 web view gets destroyed when app goes to background

Workaround Attempts

I've tried several approaches but none work:

• App lifecycle management
• State persistence with SharedPreferences
• Different launchMode settings in AndroidManifest
• CustomTabs configuration

Request

Could you please:

1. Acknowledge this as a known issue if it exists
2. Provide a solution for maintaining authentication flow state
3. Consider adding an option to use embedded webview instead of external browser
4. Add documentation about this limitation and best practices

This is a critical UX blocker that prevents users from completing registration. Any guidance would be greatly appreciated!

Environment

• Flutter: 3.35.3
• Android: API 33
• Device: Physical device (not emulator)